..We discuss the limitations of these studies, the reasons for their disagreement with previous negative findings, the nature of the muscle afferent feedback stimulus and the need for future investigations. ..

Role of central/peripheral chemoreceptors and their interdependence in the pathophysiology of sleep apnea

..Finally, we discuss the effects of preventing transient hypocapnia (via selective increases in FICO(2)) on centrally mediated types of periodic breathing and even some varieties of cyclical obstructive sleep apnea...

New perspectives concerning feedback influences on cardiorespiratory control during rhythmic exercise and on exercise performance

..To solve many of these difficult basic problems and to understand how systems operate alone and in combination in an integrated fashion, truly experimental integrative physiological approaches are required in both humans and animals...

Update in the understanding of respiratory limitations to exercise performance in fit, active adults

..Exercise in the hypoxic environments of even moderately high altitudes will greatly exacerbate the negative influences of these respiratory system limitations to exercise performance, especially in highly fit individuals...

Respiratory system determinants of peripheral fatigue and endurance performance

..Finally, evidence is presented which points to a significant role for unstable, central respiratory motor output as a significant contributor to upper airway narrowing and obstruction during sleep...

Pathophysiology of sleep apnea

Jerome A DempseyThe John Rankin Laboratory of Pulmonary Medicine, Departments of Population Health Sciences and of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USAPhysiol Rev 90:47-112. 2010

..We discuss future research into understanding the pathophysiology of sleep apnea as a basis for uncovering newer forms of treatment of both the ventilatory disorder and its multiple sequelae...

..This inhibition of inspiratory motor output is alinear within an inspiration and reflects the activation of UA pressure-sensitive receptors by UA distortion, with greater distortion possibly occurring later in the effort...

..We conclude that UA closure and deformation will cause significant TE prolongation during all states of consciousness and activation of the genioglossus muscle during wakefulness and NREM sleep but not during REM sleep...

A W SheelDepartment of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin Madison, Madison, WI, USAJ Physiol 537:277-89. 2001

..Q(L) and increases in LVR. We attribute these changes to a metaboreflex originating in the diaphragm. Diaphragm and forearm muscle fatigue showed very similar time-dependent effects on LVR and .Q(L)...

Response time and sensitivity of the ventilatory response to CO2 in unanesthetized intact dogs: central vs. peripheral chemoreceptors

..5. We conclude that the normal exercise-induced O(2) desaturation during heavy-intensity endurance exercise contributes significantly to exercise performance limitation in part because of its effect on locomotor muscle fatigue...

Keisho KatayamaThe John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53706, USAJ Appl Physiol 103:1942-9. 2007

..We conclude that 3-wk CIH reduced the sensitivity of the ventilatory response to transient hypocapnia and thereby increased the CO(2) reserve, i.e., the propensity for apnea was reduced...

..01 for the apnoeic threshold). We concluded that hypoxia causes a narrowing of the difference between the baseline P(ET,CO2) and the hypopnoea/apnoeic threshold P(ET,CO2), which could increase the likelihood of ventilatory instability...

..J Appl Physiol 94: 155-164, 2003). We conclude that hypocapnia sensed at the carotid body chemoreceptor is required for the initiation of apnea following a transient ventilatory overshoot in non-rapid eye movement sleep...

..2%) or hyperoxia (6.7%). These results demonstrate that quadriceps muscle fatigability during isolated muscle exercise is exacerbated in acute hypoxia, and these effects are independent of the relative exercise intensity...

Gregory M BlainThe John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USAJ Physiol 588:2455-71. 2010

..We conclude that the gain of the CNS CO(2)/H(+) chemoreceptors in dogs is critically dependent on CB afferent activity and that CNS-CB interaction results in hyperadditive ventilatory responses to central hypercapnia...

The assessment of upper airway patency during apnea using cardiogenic oscillations in the airflow signal

..35). We suggest that feedback from fatiguing muscle plays an important role in the determination of central motor drive and force output, so that the development of peripheral muscle fatigue is confined to a certain level...

..Recent evidence suggests that these respiratory influences contribute significantly to sympathetic vasomotor outflow and to the distribution of systemic vascular conductances and blood flow in the exercising human...

Influence of arterial O2 on the susceptibility to posthyperventilation apnea during sleep

..These findings indicate that posthyperventilation apnea is initiated by the peripheral chemoreceptors and that the varying susceptibility to apnea during hypoxia vs. hyperoxia is influenced by the relative activity of these receptors...

..Observations in both humans and animals are cited to demonstrate the marked plasticity of the CO2 reserve and, therefore, the propensity for apneas and periodic breathing, in response to changing background ventilatory stimuli...

On the normal variability of gas exchange efficiency during exercise: does sex matter?

..They may also act as a protective parallel vascular network limiting the rise in regional pulmonary vascular pressure while preserving cardiac output during exercise...

Mechanisms of the cerebrovascular response to apnoea in humans

Tadeusz PrzybyłowskiDepartment of Population Health Sciences, University of Wisconsin Madison, The John Rankin Laboratory of Pulmonary Medicine, and the Middleton Veterans Administration Hospital, 53705, USAJ Physiol 548:323-32. 2003

..These findings indicate that there is considerable hypoxia-induced sympathetic restraint of muscle blood flow during both mild and moderate exercise, which helps to maintain arterial blood pressure in hypoxia...

Research Grants1

..These latter studies conduced in sleep are important to testing the sensitivity of respiratory control mechanisms to mechanical feedback-a problem which remains relatively unexplored, especially in the human. ..